U.S. patent application number 14/419940 was filed with the patent office on 2015-07-23 for downhole heterogeneous proppant.
This patent application is currently assigned to Schlumberger Technology Corporation. The applicant listed for this patent is Ruslan Ramilevich Isangulov, Konstantin Mikhailovich Lyapunov, Anatoly Vladimirovich Medvedev, Oleg Medvedev, Alexander Vuacheslavovich Mikhaylov, Rod William Shampine, Geza Horvath Szabo, Konstantin Viktorovich Vidma. Invention is credited to Ruslan Ramilevich Isangulov, Konstantin Mikhailovich Lyapunov, Anatoly Vladimirovich Medvedev, Oleg Medvedev, Alexander Vuacheslavovich Mikhaylov, Rod William Shampine, Geza Horvath Szabo, Konstantin Viktorovich Vidma.
Application Number | 20150204177 14/419940 |
Document ID | / |
Family ID | 50068406 |
Filed Date | 2015-07-23 |
United States Patent
Application |
20150204177 |
Kind Code |
A1 |
Isangulov; Ruslan Ramilevich ;
et al. |
July 23, 2015 |
DOWNHOLE HETEROGENEOUS PROPPANT
Abstract
A technique facilitates treatment of a subterranean formation. A
proppant and a proppant carrier fluid are delivered to a
subterranean location for treatment of the formation. At the
subterranean location, heterogeneities of proppant structures are
generated with the proppant and the proppant carrier fluid. The
heterogeneous proppant structures are then transported into the
subterranean formation to improve conductivity.
Inventors: |
Isangulov; Ruslan Ramilevich;
(Russia, RU) ; Vidma; Konstantin Viktorovich;
(Novosibirsk, RU) ; Medvedev; Oleg; (Alberta,
CA) ; Lyapunov; Konstantin Mikhailovich;
(Novosibirsk, RU) ; Medvedev; Anatoly Vladimirovich;
(Novosibirsk, RU) ; Mikhaylov; Alexander
Vuacheslavovich; (Calgary, CA) ; Shampine; Rod
William; (Houston, TX) ; Szabo; Geza Horvath;
(Sugar Land, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Isangulov; Ruslan Ramilevich
Vidma; Konstantin Viktorovich
Medvedev; Oleg
Lyapunov; Konstantin Mikhailovich
Medvedev; Anatoly Vladimirovich
Mikhaylov; Alexander Vuacheslavovich
Shampine; Rod William
Szabo; Geza Horvath |
Russia
Novosibirsk
Alberta
Novosibirsk
Novosibirsk
Calgary
Houston
Sugar Land |
TX
TX |
RU
RU
CA
RU
RU
CA
US
US |
|
|
Assignee: |
Schlumberger Technology
Corporation
Sugar Land
TX
|
Family ID: |
50068406 |
Appl. No.: |
14/419940 |
Filed: |
August 7, 2012 |
PCT Filed: |
August 7, 2012 |
PCT NO: |
PCT/RU2012/000639 |
371 Date: |
February 6, 2015 |
Current U.S.
Class: |
166/280.1 ;
166/177.5 |
Current CPC
Class: |
E21B 43/267
20130101 |
International
Class: |
E21B 43/267 20060101
E21B043/267 |
Claims
1. A method for stimulating a subterranean formation by hydraulic
fracturing, comprising: delivering a slurry, comprising a proppant
and a proppant carrier fluid, down through a wellbore to a downhole
tool; using the downhole tool to generate heterogeneous proppant
structures; and delivering the heterogeneous proppant structures
into a surrounding formation.
2. The method as recited in claim 1, wherein delivering comprises
delivering the proppant and the proppant carrier fluid to the
downhole tool along a single flow path.
3. The method as recited in claim 1, wherein delivering comprises
delivering the proppant and the proppant carrier fluid to the
downhole tool along a plurality of flow paths in which at least one
of the flow paths carries fluid with a relatively higher
concentration of proppant.
4. The method as recited in claim 1, wherein using the downhole
tool comprises deploying the downhole tool in close proximity to a
perforation zone of the wellbore communicating with the surrounding
formation.
5. The method as recited in claim 1, wherein using the downhole
tool comprises using an active downhole tool.
6. The method as recited in claim 1, wherein using the downhole
tool comprises using a passive downhole tool.
7. The method as recited in claim 1, further comprising coupling
the downhole tool to a bottom of a slurry line.
8. The method as recited in claim 1, wherein using comprises using
the downhole tool to apply centrifugal forces to the proppant and
the proppant fluid to create the heterogeneous proppant
structures.
9. The method as recited in claim 1, wherein using comprises using
the downhole tool to temporarily accumulate the proppant while
allowing the proppant fluid to pass.
10. The method as recited in claim 1, wherein using comprises using
the downhole tool to temporarily block flow of proppant and to
subsequently release the blocked proppant.
11. The method as recited in claim 1, wherein using comprises using
the downhole tool to direct the proppant and the proppant fluid
along a tortuous path to create the heterogeneous proppant
structures.
12. The method as recited in claim 1, wherein using comprises using
the downhole tool to create controlled turbulence with respect to
flow of the proppant and the proppant fluid to create the
heterogeneous proppant structures.
13. The method as recited in claim 1, wherein using comprises using
the downhole tool to separate the proppant and the proppant fluid
into two different flows having different concentrations of
proppant.
14. The method as recited in claim 1, wherein using comprises using
the downhole tool to periodically interrupt the flow of proppant to
create oscillations that result in the heterogeneous proppant
structures.
15. The method as recited in claim 1, wherein using comprises using
the downhole tool to create at least one of heterogeneous pressure
and heterogeneous temperature distribution with respect to flow of
the proppant and the proppant carrier fluid to create the
heterogeneous proppant structures.
16. The method as recited in claim 1, wherein using comprises using
the downhole tool to create slurry bubbles without interrupting the
flow of proppant to create the heterogeneous proppant
structures.
17. A system for stimulating a subterranean formation, comprising:
a tubing string deployed in a wellbore and along which a slurry,
comprising a proppant and a proppant carrier fluid, is delivered
downhole to a desired well zone; and a tool positioned downhole to
receive the proppant and the proppant carrier fluid delivered down
along the tubing string, the tool comprising a mechanism to create
heterogeneous proppant structures.
18. The system as recited in claim 17, wherein the mechanism
comprises a centrifugal mechanism to separate the proppant and the
proppant carrier fluid into the heterogeneous proppant
structures.
19. The system as recited in claim 17, wherein the mechanism
comprises a proppant accumulative mechanism which selectively
collects and releases the proppant to create the heterogeneous
proppant structures.
20. The system as recited in claim 17, wherein the mechanism
comprises a mechanism which introduces controlled turbulence into
flow of the proppant and the proppant carrier fluid to create the
heterogeneous proppant structures.
21. The system as recited in claim 17, wherein the mechanism
comprises a mechanism which introduces heterogeneous pressure
and/or temperature distribution into flow of the proppant and the
proppant carrier fluid to create the heterogeneous proppant
structures.
22. The system as recited in claim 17, wherein the mechanism
comprises a mechanism which periodically interrupts the flow of
proppant to create the heterogeneous proppant structures.
23. The system as recited in claim 17, wherein the mechanism
comprises a mechanism which creates slurry bubbles without
interrupting the flow of proppant to create the heterogeneous
proppant structures.
24. The system as recited in claim 17, wherein the tubing string
comprises a single flow path for both the proppant and the proppant
carrier fluid.
25. A method for treating a subterranean formation, comprising:
delivering a proppant and a proppant carrier fluid to a
subterranean location; at the subterranean location, generating
heterogeneities of proppant structures with the proppant and the
proppant carrier fluid; and transporting heterogeneous proppant
structures into a subterranean formation.
26. The method as recited in claim 25, wherein generating comprises
generating the heterogeneity of proppant structures with a tool
mounted at an end of a slurry line in a wellbore.
27. The method as recited in claim 25, wherein delivering comprises
delivering the proppant and the proppant carrier fluid along at
least one flow path of a tubing string deployed in a wellbore.
Description
BACKGROUND
[0001] In producing oil and gas, a variety of subterranean geologic
formations lack sufficient permeability for optimal production of
the hydrocarbons. The low permeability reduces the potential
production rate of the hydrocarbon fluids. However, the flow rate
can be increased by performing stimulation treatments, such as
hydraulic fracturing, on the formation. By way of example,
hydraulic fracturing may be performed by hydraulically injecting a
fracturing fluid at high pressure, e.g. in excess of 10,000 psi,
into the wellbore and ultimately into the surrounding formation.
Once the pressure exceeds a threshold value, the formation
strata/rock fractures and the fracturing fluid propagates into the
formation. The fracturing fluid carries proppant particles into the
extending fractures, and the proppant particles are deposited in
the created fractures to prop open the fractures. By delivering the
proppant into the fractures, the potential flow of recoverable
fluid is improved although the homogeneous mixture of proppant in
the fracturing fluid limits the improvement. The homogeneous matrix
of packed proppant affects the fracture conductivity which is the
ability of fluids to flow from the formation, through the matrix of
packed proppant, and into the production wellbore.
[0002] Various methods have been employed for controlling the
proppant pack permeability in an effort to enhance hydraulic
conductivity. For example, U.S. Pat. Nos. 3,592,266; 3,850,247;
5,411,091; 6,776,235; 7,213,651; and 7,451,812 propose high
conductivity channels by pumping alternating intervals of
fracturing slurries which are different in at least one of their
parameters. Many of these techniques assume that heterogeneity
introduced at an early stage of hydraulic fracturing treatment will
be preserved throughout the treatment process. However, one of the
main problems in creating heterogeneities of proppant structures at
the surface when fluids are mixed and pumped into the wellbore is a
homogeneous dispersion of the heterogeneities upon arriving at the
perforation or fracture.
SUMMARY
[0003] In general, the present disclosure provides a system and
method for use in treating a subterranean formation. A proppant and
a proppant carrier fluid are combined into a slurry and delivered
to a subterranean location to facilitate treatment of the
formation. At the subterranean location, heterogeneities of
proppant structures are generated with the proppant and the
proppant carrier fluid. The heterogeneous proppant structures are
then transported into the subterranean formation to greatly improve
conductivity.
[0004] However, many modifications are possible without materially
departing from the teachings of this disclosure. Accordingly, such
modifications are intended to be included within the scope of this
disclosure as defined in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] Certain embodiments will hereafter be described with
reference to the accompanying drawings, wherein like reference
numerals denote like elements. It should be understood, however,
that the accompanying figures illustrate the various
implementations described herein and are not meant to limit the
scope of various technologies described herein, and:
[0006] FIG. 1 is an illustration of an example of a system, e.g. a
well system, deployed to deliver a treatment to a subterranean
formation, according to an embodiment of the disclosure;
[0007] FIG. 2 is a schematic illustration of an example of a tool
positioned at a downhole location and comprising a mechanism to
create heterogeneous proppant structures from proppant and the
proppant carrier fluid received by the tool, according to an
embodiment of the disclosure;
[0008] FIG. 3 is a schematic illustration of another example of a
tool to create heterogeneous proppant structures at a subterranean
location, according to an embodiment of the disclosure;
[0009] FIG. 4 is a schematic illustration of another example of a
tool to create heterogeneous proppant structures at a subterranean
location, according to an embodiment of the disclosure;
[0010] FIG. 5 is a schematic illustration of another example of a
tool to create heterogeneous proppant structures at a subterranean
location, according to an embodiment of the disclosure;
[0011] FIG. 6 is a schematic illustration similar to that of FIG. 5
but showing the tool in a different operational position, according
to an embodiment of the disclosure;
[0012] FIG. 7 is a schematic illustration similar to that of FIG. 6
but showing the tool in a different operational position, according
to an embodiment of the disclosure;
[0013] FIG. 8 is a schematic illustration of another example of a
tool to create heterogeneous proppant structures at a subterranean
location, according to an embodiment of the disclosure;
[0014] FIG. 9 is a schematic illustration similar to that of FIG. 8
but showing the tool in a different operational position, according
to an embodiment of the disclosure;
[0015] FIG. 10 is a schematic illustration similar to that of FIG.
9 but showing the tool in a different operational position,
according to an embodiment of the disclosure;
[0016] FIG. 11 is a schematic illustration of another example of a
tool to create heterogeneous proppant structures at a subterranean
location, according to an embodiment of the disclosure;
[0017] FIG. 12 is a cross-sectional top view of the tool
illustrated in FIG. 11, according to an embodiment of the
disclosure;
[0018] FIG. 13 is a schematic illustration of another example of a
tool to create heterogeneous proppant structures at a subterranean
location, according to an embodiment of the disclosure;
[0019] FIG. 14 is a schematic illustration of another example of a
tool to create heterogeneous proppant structures at a subterranean
location, according to an embodiment of the disclosure;
[0020] FIG. 15 is a schematic illustration of another example of a
tool to create heterogeneous proppant structures at a subterranean
location, according to an embodiment of the disclosure;
[0021] FIG. 16 is a schematic illustration of another example of a
tool to create heterogeneous proppant structures at a subterranean
location, according to an embodiment of the disclosure;
[0022] FIG. 17 is an enlarged view of the tool illustrated in FIG.
16, according to an embodiment of the disclosure;
[0023] FIG. 18 is a schematic illustration of another example of a
tool to create heterogeneous proppant structures at a subterranean
location, according to an embodiment of the disclosure;
[0024] FIG. 19 is a schematic top view of the tool illustrated in
FIG. 18, according to an embodiment of the disclosure;
[0025] FIG. 20 is a schematic illustration of another example of a
tool to create heterogeneous proppant structures at a subterranean
location, according to an embodiment of the disclosure;
[0026] FIG. 21 is a schematic illustration of another example of a
tool to create heterogeneous proppant structures at a subterranean
location, according to an embodiment of the disclosure;
[0027] FIG. 22 is a schematic illustration of a spiraling
concentration of proppant material distributed by the tool
illustrated in FIG. 21, according to an embodiment of the
disclosure;
[0028] FIG. 23 is a schematic illustration of proppant structures
distributed into a surrounding formation in a generally concentric
orientation, according to an embodiment of the disclosure;
[0029] FIG. 24 is a schematic illustration of another example of a
portion of a tool used to create heterogeneous proppant structures
at a subterranean location, according to an embodiment of the
disclosure;
[0030] FIG. 25 is a schematic illustration of another example of a
portion of a tool to create heterogeneous proppant structures at a
subterranean location, according to an embodiment of the
disclosure;
[0031] FIG. 26 is a schematic illustration of another example of a
tool to create heterogeneous proppant structures at a subterranean
location, according to an embodiment of the disclosure; and
[0032] FIG. 27 is a schematic illustration of proppant structures
distributed into a surrounding formation in a generally
perpendicular orientation with respect to the well, according to an
embodiment of the disclosure.
DETAILED DESCRIPTION
[0033] In the following description, numerous details are set forth
to provide an understanding of some embodiments of the present
disclosure. However, it will be understood by those of ordinary
skill in the art that the system and/or methodology may be
practiced without these details and that numerous variations or
modifications from the described embodiments may be possible.
[0034] The disclosure herein generally involves a system and
methodology for treating a subterranean formation. For example, the
system and methodology may be employed to facilitate a fracturing
operation with respect to a subterranean formation surrounding a
wellbore. In a variety of fracturing or other treatment
applications, a proppant and a proppant carrier fluid are delivered
to the subterranean location to facilitate treatment of the
formation. When employed in fracturing, the proppant and proppant
carrier fluid may be combined into a slurry to form a variety of
fracturing fluids. At the subterranean location, heterogeneities of
proppant structures are generated with the proppant and the
proppant carrier fluid. For example, a subterranean tool, such as a
bottom hole tool located in a wellbore, may be employed at the
subterranean location to create heterogeneous proppant structures.
The heterogeneous proppant structures are then transported into the
subterranean formation to improve conductivity.
[0035] Fracturing fluids may comprise a variety of materials, such
as proppant and removable proppant-spacing material. The
proppant-spacing material may be designed to function in forming
open channels and spaces around clusters of proppant. Such
extramatrical channel-forming materials, including proppant-spacing
particles, are sometimes referred to as channelant.
[0036] In some applications, the term "proppant" may be employed to
describe materials comprising channelant and sized particles which
may be mixed with a proppant carrier fluid to help provide an
efficient conduit for production of fluid from the
formation/reservoir to the wellbore. Proppant may comprise
naturally occurring sand grains or gravel, man-made or specially
engineered proppants, e.g. resin-coated sand, or high-strength
ceramic materials, e.g. sintered bauxite. Proppant materials also
may comprise fibers, such as fibers formed from glass, ceramics,
carbon (including carbon-based compounds), metal (including
metallic alloys), polymeric materials (e.g. PLA, PGA, PET, polyol)
and other materials or combinations of such materials.
[0037] The proppant also may be formed in a variety of sizes or
ranges of sizes of material having mixed shapes, variable
diameters, or other properties that yield, for example,
high-density and high-strength properties to increase fracture
conductivity. By way of specific examples, hydraulic fracturing can
use up to 50 tons or more of proppant in which 10-15 tons have
particle diameters from 0.002 to 0.1 mm; 15-30 tons have particle
diameters from 0.2 to 0.6 mm; and 10-15 tons have particle
diameters from 0.005 to 0.05 mm. Proppant size, however, may vary
from job to job and from stage to stage. In some examples, the
proppant comprises particles having an average particle size of
from about 0.15 mm to about 2.5 mm; and additional examples of size
ranges are from about 0.25-0.43 mm, 0.43-0.85 mm, 0.85-1.18 mm,
1.18-1.70 mm, and 1.70-2.36 mm.
[0038] As described in greater detail below, the proppant is used
in a system and methodology for generating heterogeneities of
proppant structures at a subterranean location (in situ) during a
treatment operation, e.g. during a perforation/hydraulic fracturing
operation. In a variety of well applications, the system and
methodology may be used in stimulating, e.g. hydraulically
fracturing, a subterranean formation penetrated by a wellbore
combined with placing propping agents in a fracture heterogeneously
to further enhance conductivity.
[0039] Referring generally to FIG. 1, an example of a subterranean
treatment system is illustrated as comprising a well system having
a tubing string deployed in a well. The well system can be used in
a variety of well applications, including onshore applications and
offshore applications. In this example, the tubing string is
illustrated as deployed in a generally vertical wellbore, however
the tubing string may be deployed in a variety of wells including
various vertical and deviated wells. The embodiments described
below may be employed to facilitate, for example, fracturing
operations in well applications and in other types of
applications.
[0040] In the example illustrated in FIG. 1, a well system 30 is
deployed in a wellbore 32 and comprises a tubing string 34 having
at least one flow path 36. In the example illustrated, a plurality
of flow paths 36 is represented by arrows 38 and may be created by
tubular structures 40. A proppant delivery system 42 delivers a
proppant 48 and proppant carrier fluid 50 in the form of a slurry,
down along tubing string 34 to a tool 44. In a fracturing
application, for example, fracturing fluid may be delivered down
through tubing string 34 and into the tool 44 which may be
positioned at a bottom hole end of the tubing string 34. In some
applications, the tubing string 34 comprises a slurry line, e.g. a
coiled tubing slurry line, and tool 44 is coupled to the slurry
line at its lower end. Tool 44 comprises a mechanism 46 to generate
heterogeneities of proppant structures at the downhole location
during a treatment operation, such as a fracturing operation.
[0041] During a fracturing operation, fracturing fluid is pumped
down along tubing string 34 and may comprise proppant 48 and
proppant carrier fluid 50, e.g. a clean fluid/lower proppant
concentration fluid, which carries the proppant 48. Depending on
the parameters of a given application, the proppant 48 and proppant
carrier fluid 50 may be delivered downhole along a single flow path
36 or along a plurality of flow paths 36. The fracturing
fluid/slurry comprising proppant 48 and proppant carrier fluid 50
is delivered to downhole tool 44, and mechanism 46 is employed to
generate heterogeneous proppant structures 52 which have a
different concentration of proppant than the surrounding fluid. For
example, the proppant structures 52 may comprise higher
concentrations of proppant 48.
[0042] The fracturing fluid, comprising the newly (and locally)
formed heterogeneous proppant structures 52, is discharged by tool
44 into a surrounding formation 54 of a well zone 55 under
sufficient pressure to create a fracture or fractures 56 in the
formation 54. In the example illustrated, tool 44 disperses the
fracturing fluid 48, 50 and its heterogeneous proppant structures
52 through one or more perforations 58 forming a perforation zone
of the wellbore 32 communicating with the surrounding formation 54.
The perforations extend outwardly through a wall forming wellbore
32 and into formation 54. Forming the heterogeneous proppant
structures 52 in close proximity to the perforation zone at the
downhole location helps maintain the heterogeneity as the material
is moved into fracture 56, thus improving the conductivity of well
fluid moving from formation 54, along fracture 56, and into
wellbore 32.
[0043] Various embodiments of tool 44 may be used to implement the
downhole generation of heterogeneities of proppant structures and
to thus create highly conductive hydraulic fractures. Referring
generally to FIGS. 2 and 3, certain embodiments of tool 44 may
utilize centrifugal forces to generate the heterogeneous proppant
structures 52. In the example illustrated in FIG. 2, tool 44
utilizes mechanism 46 in the form of a hydrocyclone 60 which may be
active or passive. An active form of hydrocyclone 60 refers to a
powered mechanism employing a motor or other motive source to spin
the proppant 48 and proppant carrier fluid 50 in a manner that
separates the proppant 48 and proppant carrier fluid 50 into
streams having relatively higher concentration and lower
concentration of proppant 48. A passive form of hydrocyclone 60 is
one that uses the natural flow of the proppant 48 and proppant
carrier fluid 50 to create the centrifugal forces separating the
proppant 48 and proppant carrier fluid 50 into flow streams which
may comprise different concentrations of proppant 48.
[0044] Regardless of whether the mechanism 46 is active or passive,
the tool 44 illustrated in FIG. 2 receives the proppant 48 and
proppant carrier fluid 50 along a single flow path, e.g. through a
slurry line 62. The proppant 48 and proppant carrier fluid 50 is
delivered to hydrocyclone 60 through an inlet 64 and is directed in
a circular, e.g. spiral, pattern to induce centrifugal forces which
separate the proppant 48 and proppant carrier fluid 50 into a
higher concentration flow of proppant 48 which exits through an
outlet 66 and a lower concentration flow of proppant 48 which exits
through a second outlet 68. The flow path of the higher
concentration flow is illustrated by arrow 70 and the flow path of
the lower concentration flow is illustrated by arrow 72. In this
particular example, tool 44 also may comprise a supplemental
mechanism 74 designed to receive the higher concentration flow 70
and to separate the higher concentration flow into independent or
separated heterogeneous proppant structures 52. Some examples of
such mechanisms for generating independent heterogeneous proppant
structures 52 are described in greater detail below.
[0045] As illustrated in the embodiment of FIG. 3, however, the
heterogeneous proppant structures 52 may be created via a continual
stream of concentrated proppant 48. In this example, at least one
flow path 36 is used for delivering proppant 48 and proppant
carrier fluid 50 to a perforation zone. The heterogeneous proppant
structures 52 can again be generated by tool 44 in the form of
hydrocyclone 60 located downhole at, for example, a bottom end of
slurry line 62. In this example, the higher concentration flow 70
of proppant 48 is discharged through a nozzle or other suitable
device 76 for distribution through perforations 58 and into
fracture 56. The decomposition of the slurry flow into two flows is
based on the centrifugal forces induced in tool 44. Homogeneous
mixing of the higher concentration flow 70 with the lower
concentration flow 72 is reduced or prevented by creating spiral
slurry strings 78. Due to the close proximity of the perforation
zone, the spiral slurry strings 78 remain unmixed before being
divided by the perforations 58 into heterogeneous proppant
structures 52. Consequently, the heterogeneous proppant structures
52 are flowed into the fracture 56 heterogeneously.
[0046] In this latter example, the downhole tool 44 may be used to
decompose the slurry flow into two flows by utilizing different
geometries of the tool. For example, tool 44 may be in the form of
a hydrocyclone without rotating parts or in the form of a
centrifugal pump having rotating parts. The spiral slurry strings
may be created within a surrounding casing 80 by rotating
outlet/nozzle 76 to create a spiral flow of the higher
concentration material or by rotating the entire tool 44 along a
vertical axis. Accordingly, the tool 44 may be an active tool using
the energy of engines or other external sources, or the tool may be
passive and use the energy of the flowing slurry. It should be
noted that decomposition of the slurry flow also can be affected by
the physical properties of the slurry, e.g. flow speed, slurry
density, or other slurry characteristics.
[0047] Referring generally to FIG. 4, another embodiment of tool 44
is illustrated. In this embodiment, the proppant 48 and proppant
carrier fluid 50 are again delivered downhole as a slurry 82 along
single or plural flow paths 36. As illustrated, the proppant 48 and
proppant carrier fluid 50 may be delivered along single flow path
36 within slurry line 62 to a downhole location below a packer 84.
Packer 84 separates the slurry line 62 from the surrounding casing
80. In this embodiment, tool 44 accumulates the proppant 48 from
the slurry 82 and allows the separated clean fluid to pass through
the tool 44. The accumulated proppant 48 is released periodically
in a given size, volume or mass into the separated clean fluid
flowing down through perforations 58. The periodically released
proppant 48 creates the heterogeneous proppant structures 52 which
are carried down through perforations 58 and into fracture 56.
[0048] In this embodiment, the tool 44 may comprise a sieve 88
which is pivotably mounted within slurry line 62 for pivoting
motion about an axis 90. The sieve 88 is designed to accumulate the
proppant 48 from the slurry 82 while allowing the clean fluid to
pass through until a desired amount of proppant 48 is collected. A
trigger mechanism 92, e.g. motor, spring mechanism, releasable
latch, or other suitable trigger mechanism, is then actuated to
enable rotation of the sieve 88 to a position which dumps the
proppant 48 to form a heterogeneous proppant structure 52. This
process is repeated to create the plurality of heterogeneous
proppant structures 52 routed into fracture 56.
[0049] In a similar example, the proppant 48 is accumulated along a
plurality of plates or ledges 94, as illustrated in FIGS. 5-7. In
this embodiment, the ledges 94 are located at different positions
along the tool 44 such that the slurry 82 is forced to flow along a
tortuous path 96 between the ledges 94 in a manner that causes
proppant 48 to accumulate on the ledges 94, as illustrated in FIG.
5. A trigger device (e.g. see trigger mechanism 92 in FIG. 4) is
employed to rapidly pivot the ledges 94 through, for example,
90.degree. to release the accumulated proppant 48, as illustrated
in FIG. 6. A spring mechanism 98 or other suitable mechanism may be
used to return the ledges 94 back to their original positions to
again begin accumulating proppant 48, as illustrated in FIG. 7.
This process may be repeated to create the heterogeneous proppant
structures 52 containing more highly concentrated proppant 48, as
also illustrated in FIG. 7. The heterogeneous proppant structures
52 are carried through perforations 58 and transported into
fracture 56.
[0050] The embodiments illustrated in FIGS. 4-7 may utilize a
variety of configurations and tool geometries to generate the
proppant structure heterogeneities. For example, tool 44 may
comprise rotating sieves, meshes, or screens to accumulate the
proppant 48. The tool 44 also may utilize fluid-induced vibrations
or it may comprise self-opening assemblies to provide controlled
release of proppant as heterogeneous proppant structures 52 in
desired sizes, volumes or portions. Additionally, the tool 44 may
utilize a variety of trigger mechanisms 92 for releasing proppant
48 in the form of heterogeneous proppant structures 52 based on
pressure, mass of proppant, time of accumulation, or other
triggering events. Additionally, tool 44 may be actively or
passively operated by using an external source of energy or by
using the energy of the flow, respectively.
[0051] Referring generally to FIGS. 8-10, another embodiment of
tool 44 is illustrated. Similar to the previously described
embodiments, the tortuous path 96 (or paths) is routed through tool
44 to direct the slurry 82 through sharp changes in direction. Due
to the sharp changes of direction in the flowing slurry, proppant
48 is accumulated at elbows 100 formed along the tortuous path 96,
as illustrated in FIG. 8. A trigger device (e.g. see trigger
mechanism 92 in FIG. 4) is employed to rapidly pivot the elbows 100
in a manner which releases the accumulated proppant 48, as
illustrated in FIG. 9. A spring mechanism 98 or other suitable
mechanism may be used to restore the elbows 100 so as to again
begin accumulating proppant 48, as illustrated in FIG. 10. This
process may be repeated to create the heterogeneous proppant
structures 52 containing more highly concentrated proppant 48 (see
FIG. 10). The heterogeneous proppant structures 52 are flowed
through perforations 58 and transported into fracture 56.
[0052] In the latter embodiment, the proppant structure
heterogeneities 52 may be created by various tool configurations.
For example, the tool 44 may be designed with different numbers and
configurations of tortuous flow paths 96. The tool 44 also may
contain various configurations, mechanisms and ports in different
numbers to accumulate proppant 48 along the tortuous paths 96. The
releasable elbows 100 also may be formed with ledges, plates, or
other mechanisms designed to release heterogeneous proppant
structures 52 of predetermined sizes, volumes, or portions. Several
types of triggers 92 also may be employed to release the
accumulated proppant 48 based on, for example, pressure, mass of
proppant, time of accumulation, or other factors. Different types
of flow paths 96 may be established through the tool 44 to
accommodate different types of proppant 48.
[0053] In another embodiment, the tool 44 comprises a bottom hole
tool which may receive slurry along individual or plural flow paths
36. In this example, tool 44 is designed to introduce controlled
turbulence to the flow pattern of the slurry 82 which, in turn,
creates zones of high proppant concentration and zones of low
proppant concentration in the slurry flow, as illustrated in FIGS.
11 and 12. As with previously described embodiments, these
heterogeneities are created downhole and transported directly
through the perforations 58 for distribution into fracture 56.
[0054] By way of example, the bottom hole tool 44 may be coupled to
a bottom end of the slurry line 62, and a plurality of propeller
devices 102, having propellers 104, may be deployed within the
tubing string 34, e.g. within the slurry line 62. The propeller
devices 102 are positioned apart from each other at different
angles with respect to a vertical axis along slurry line 62. The
propellers 104 may be rotated in opposite directions at different
angles to induce turbulence to the flow of slurry 82 in tubing 62.
As a result, zones with different concentrations of proppant 48 are
created in the flow and this leads to creation of heterogeneous
proppant structures 52. The proppant structures 52 continued to
move with the flow out through perforations 58 and into the
fracture 56. Propellers 104 may be powered by power sources or by
the energy of the flowing slurry.
[0055] Different types of proppant structure heterogeneities may be
achieved by, for example, varying the geometry of tool 44.
Additionally, the propeller devices 102 may be combined with other
components, such as complex pathways and proppant accumulation
regions to facilitate creation of the controlled turbulence and
structures 52. Additionally, the propellers 104 may have different
numbers of vanes and vane configurations, may be rotated at
different speeds, and may be started and stopped according to
predetermined schedules. The distance between propellers 104 and
the relative angles of the propellers 104 also can be adjusted to
affect the creation of heterogeneous proppant structures 52. The
properties of the slurry flow, e.g. flow rate, proppant
concentration, and concentration profile, also may be used to
control the concentration of proppant 48 into the heterogeneous
proppant structures 52.
[0056] Referring generally to FIG. 13, the downhole concentration
of proppant 48 into heterogeneous proppant structures 52 also may
be accomplished by designing tool 44 to create pressure pulses 106
having given pressure amplitudes and frequencies in the homogeneous
flow of slurry 82. The pressure pulses 106 may be created by pulse
generators 108, and the amplitudes and frequencies may be changed
while flowing the slurry. The pressure pulses 106 may be designed
to create standing pressure waves and also may be designed to
generate heterogeneous pressure distribution along the slurry flow.
The heterogeneous pressure distribution leads to heterogeneous flow
disturbance, heterogeneous density and velocity distributions, and
ultimately to the creation of heterogeneous proppant structures 52
for delivery into fracture 56.
[0057] In this embodiment, the tool 44 may again be constructed in
a variety of configurations to provide different ways of generating
proppant structure heterogeneities. For example, tool 44 may
utilize different forms of pulse generations or different types of
pressure amplitudes and/or pressure pulse frequencies. The tool 44
may contain rotating or vibrating parts, different types of
discharge nozzles, different numbers of discharge outlets, and
other variations in configuration. Additionally, properties of the
slurry 82 may be adjusted to achieve varying effects.
[0058] Referring generally to FIG. 14, a related embodiment of tool
44 is illustrated in which heterogeneities are created downhole by
inducing pressure changes locally. For example, pressure changes
may be induced such that localized pressure downhole becomes lower
than the vapor pressure of the surrounding fluid. As a result,
created cavitations lead to local proppant agglomeration and
ultimately to creation of the heterogeneous proppant structures 52.
As with other embodiments of tool 44, the heterogeneous proppant
structures 52 are created downhole and may be immediately
transported through perforations 58 into fracture(s) 56.
[0059] By way of example, the tool 44 may comprise ultrasound wave
generators 110 which generate ultrasound waves 112. The ultrasound
radiation is of sufficient intensity to induce the local pressure
changes such that the local pressure is less than the vapor
pressure in the surrounding fluid, thus leading to heterogeneous
proppant agglomeration. Depending on the application, the number
and configuration of the ultrasound radiation generators 110 may be
changed. Additionally, various parameters of the ultrasound waves
may be adjusted, including frequencies, amplitudes, and other
parameters that lead to stationary ultrasound waves. Furthermore,
local cavitations may be created in the fluid by combining other
methods to facilitate heterogeneous proppant distribution. For
example, propellers, tortuous flow paths, accumulation mechanisms,
and/or other devices may be combined with the ultrasound wave
generators. Parameters of the slurry 82 also can affect creation of
the heterogeneous proppant structures 52 in a variety of
predetermined sizes and forms.
[0060] Referring generally to FIG. 15, another embodiment of tool
44 is illustrated in which heterogeneities are created downhole by
inducing rapid temperature changes locally downhole. For example,
temperature changes may be induced in tool 44 such that localized
temperature increases in the surrounding slurry 82 have sufficient
power to create gaseous cavities or bubbles in the fluid. As a
result, the created gaseous cavities or bubbles lead to proppant
agglomeration and ultimately to creation of the heterogeneous
proppant structures 52. As with other embodiments of tool 44, the
heterogeneous proppant structures 52 are created downhole and may
be immediately transported through perforations 58 into fracture(s)
56.
[0061] In this example, the tool 44 may comprise electromagnetic
radiation generators 114 which generate electromagnetic radiation
116 capable of rapidly creating heat energy. For example,
microwaves may be used to provide high frequency electromagnetic
waves which cause localized heating of the surrounding slurry 82.
The microwaves induce creation of gaseous cavities in the slurry 82
by this localized and rapid temperature increase, thus leading to
heterogeneous proppant agglomeration. Depending on the application,
the number and configuration of the electromagnetic radiation
generators 114 may be changed. Additionally, various parameters of
the electromagnetic radiation may be adjusted, e.g. adjustment of
frequencies and amplitudes or the use of ultrahigh frequency and
extremely high frequency electromagnetic waves. Parameters of the
slurry 82 also can affect creation of the heterogeneous proppant
structures 52 in a variety of predetermined sizes and forms.
[0062] Referring generally to FIGS. 16-17, another embodiment of
tool 44 is illustrated. In this embodiment, fracturing fluid 48, 50
is delivered along a tubing string 34 via at least two flow paths
36. For example, the fracturing fluid may be delivered through
internal tubing 40, e.g. slurry line 62, and through an annulus 118
between tubing 40 and the surrounding casing 80. For example, a
more concentrated slurry may be delivered along an interior of
tubing 40 and a fluid less concentrated with proppant 48, e.g. a
clean fluid, may be delivered through annulus 118. In this example,
tool 44 comprises a centrifugal mechanism 120 which may be designed
to circulate the slurry received from tubing 40. The tool 44
receives the slurry from tubing 40 and controls the fluid discharge
speed and direction in space to decompose the slurry flow into at
least two flows. The at least two flows of fluid exit through
outlets 122. In some applications, the tool 44 may be rotated to
create a spiral slurry string 78 (as also illustrated in FIG. 3)
which is delivered to the proximate perforation zone. The slurry
string 78 is divided into heterogeneous proppant structures 52 as
the material passes through perforations 58. As a result, the
heterogeneous proppant structures 52 are placed in the fracture 56
heterogeneously.
[0063] In some applications, the embodiment illustrated in FIGS. 16
and 17 may be adapted to receive the entire proppant 48 and
proppant carrier fluid 50 along one flow path 36. In such
application, tool 44 may comprise an additional separation
component, such as hydrocyclone 60 illustrated in FIG. 2, to
facilitate separation of the slurry into two separate flows of
relatively high proppant concentration and relatively low proppant
concentration, respectively. In such an example, the centrifugal
mechanism 120 may be coupled with the outlet port of the
hydrocyclone 60 (or other suitable tool component) through which
the higher concentration proppant stream is discharged.
[0064] Centrifugal mechanism 120 may have a variety of
configurations, including a design in the form of a rotating
cylinder 123 connected to a bottom end of tubing 40/slurry line 62.
The slurry 82 enters at the top of the rotating cylinder, as
represented by arrows 124 in FIG. 17, and flows out through outlets
122 as the centrifugal mechanism 120 is rotated about axis 126. At
least two outlets 122 may be positioned to extend from cylinder 123
generally at a lower end of the cylinder 123. The outlets 122
decompose the flow into at least two flows and direct the flows at
a tangent to a surface of the cylinder 123. The motion of the flow
may be used to create the energy for rotating cylinder 123 and for
creating spiral slurry strings 78. It should be noted that
centrifugal mechanism 120 may comprise a variety of components,
including a variety of nozzles, vanes, blades, rotating parts with
nozzles, fixed parts with nozzles, various numbers of nozzles and
nozzle configurations. Additionally, the rotation may be supplied
by a separate power source, e.g. a motor, or by the energy of the
flowing fluid.
[0065] Referring generally to FIGS. 18 and 19, another embodiment
of tool 44 is illustrated in which flow discontinuities are created
by periodic opening and closing of the slurry line 62. In this
example, a clean fluid (e.g. a fluid having a lower concentration
of proppant 48 or having no proppant 48 at all) is delivered down
along a second flow path 36, such as a flow path between slurry
line 62 and the surrounding casing 80. The opening and closing of
the slurry line 62 at tool 44 creates heterogeneous proppant
structures 52 which are carried by the clean fluid flowing along
the flow path 36 between slurry line 62 and the surrounding casing
80. The clean fluid carries the heterogeneous proppant structure 52
out through perforations 58 and into fracture 56. In this
embodiment, tool 44 also may comprise an additional separation
component or components, e.g. hydrocyclone 60, to enhance
separation and/or to allow flow of the entire proppant 48 and
proppant carrier fluid 50 along one flow path 36.
[0066] By way of example, the periodic opening and closing may be
achieved by placing a rotatable disc or discs 128 at an end of the
slurry line 62. The discs 128 comprise holes or nozzles 130 which
are rotated in opposite directions, as indicated by arrows 132 in
FIG. 19. The rotation of the discs 128 can be generated by a power
source or by the energy of the flow. The rotation of holes 130 past
one another creates periodic opening and closing of the slurry line
62 which provides controlled slurry flow discontinuities and
ultimately creates heterogeneous proppant structures 52 which may
be carried by the clean fluid flow.
[0067] It should be noted that tool 44 and rotating discs 128 may
comprise a variety of components, including a variety of gates,
holes, nozzles, vanes, blades, rotating parts with nozzles, fixed
parts with nozzles, various numbers of nozzles and nozzle
configurations. For example, the rotating discs 128 may be in the
form of cylinders with vertical open slots in each cylinder.
Additionally, the rotation may be supplied by a separate power
source, e.g. a motor, or by the energy of the flowing fluid.
Additionally, slurry and proppant parameters may be varied, e.g.
flow speed variations in each flow path, changes in slurry density,
changes in proppant concentration, changes in configuration and
number of gates, discs and nozzles, and changes in angular velocity
and direction of rotation. The tool 44 also may comprise mechanisms
to compensate for the pressure increases in the slurry line 62
during stopping and starting of the slurry flow to cause the flow
discontinuities.
[0068] Referring generally to FIG. 20, another embodiment of tool
44 is illustrated in which at least two distinct flow paths 36 are
employed for delivering proppant 48 and proppant fluid 50 to the
perforations zone. By way of example, slurry with a higher
concentration of proppant 48 may be delivered along an interior of
the slurry line 62 while a clean fluid is flowed along the
surrounding annulus. In this example, tool 44 is a bottom hole tool
coupled to a lower end of the slurry line 62 and injects
heterogeneous proppant structures 52 into the flowing clean fluid
for delivery through perforations 58 into fracture 56. The
generation of heterogeneous proppant structures 52 is achieved
based on combination of surface tension forces and clean fluid flow
drag forces. The speed and viscosity of the slurry and of the clean
fluid are different, e.g. the speed of the slurry flow is less than
the speed of the clean fluid flow. Additionally, the viscosity of
the slurry is higher than the viscosity of the clean fluid. The
bottom hole tool 44 comprises a discharge port 134 sized to create
a slurry bubble 136 which grows in size, volume and mass until the
clean fluid flow causes the slurry bubble to release and form at
least one heterogeneous proppant structure 52 which is transported
by the clean fluid through perforations 58. The creation of slurry
bubbles 136 is continually repeated to create multiple
heterogeneous proppant structures 52.
[0069] In some applications, the entire flow of proppant 48 and
proppant carrier fluid 50 is directed along one flow path 36. In
such application, tool 44 may comprise an additional separation
component, such as the hydrocyclone 60 illustrated in FIG. 2, to
facilitate downhole separation of the slurry into two separate
flows of relatively high proppant concentration and relatively low
proppant concentration, respectively. In such an example, the
discharge port 134 may be positioned downstream of the outlet port
of the hydrocyclone 60 (or other suitable tool component) through
which the higher concentration proppant stream is discharged.
Additionally, the slurry pipe 62 may be moved in an oscillating or
orbiting motion within the casing 80 to facilitate formation of the
heterogeneous proppant structures 52 with or without discharge port
134.
[0070] In this latter embodiment, tool 44 may again comprise a
variety of components, including a variety of tool geometries and
release port configurations. Additionally, slurry and proppant
parameters may be varied, and such variations may comprise changing
flow rate, changing flow rate pulsations, changing density, linear
velocity through the discharge port, combining chemical additives,
and other variations. Similarly, the clean fluid may comprise a
variety of materials and may be delivered at different flow rates,
flow rate pulsations, density, and chemical compositions.
[0071] In some applications, the tool 44 is designed with a set of
features 138, e.g. vanes, disposed along the tubing 40, e.g. along
slurry line 62. The features 138 are disposed along the inside
and/or outside of the tubular 40 such that the flowing fluid is
induced to rotate while moving down toward well zone 55. The
rotation tends to concentrate the proppant 48 toward the wall of
the tubing. At a suitable location, the width of the features/vanes
138 is increased to separate the layer of dense fluid into spiral
stripes. The spiral stripes are released proximate perforations 58
to produce the heterogeneous proppant structure 52. In some
applications, the features/vanes 138 may include a generally
straight section proximate the exit to reduce remixing of the
proppant 48. In these applications, port 134 may not be
substantially constricted relative to the diameter of the tubing
40.
[0072] Sometimes a pulsation of the proppant 48 is used in creating
proppant structures 52 along a longer (or the whole) region
containing the plurality of perforations 58. The pulsation may be
created by utilizing a cylindrical rotating head 140 (see FIG. 21)
attached to the end of internal tubing in, for example, a coaxial
arrangement. The rotating head 140 delivers a stream or streams 142
of higher concentration proppant fluid and the stream 142 may be
discharged to form a spiral 144 (see FIG. 22) inside casing 80. In
some applications, the height of the rotating head 140 may be
similar to the length of the region containing perforations 58
which extend through casing 80 and into the surrounding formation
54. However some applications may utilize a rotating head having a
height greater or lesser than the length of the region containing
perforations 58. Individual or plural slot openings 146 are
oriented in a generally circumferential direction and extend
generally parallel with an axis 148 of the rotating head 140.
[0073] Fracturing fluid of relatively high proppant concentration
passes through slot openings 146 and forms a higher concentration
vortex within a lower proppant concentration fluid 150 pumped down
through the well. The higher and lower concentration fluids are
pumped continuously so that proppant is transported radially
outward from the rotating head 140. As the streams of higher
concentration proppant fluid 142 rotate along spiral 144 into
perforations 58 through casing 80, a periodic oscillation is
created at the perforations 58. This oscillating concentration of
proppant material is pumped into the fractures 56 as proppant
structures 52.
[0074] The width of the slot openings 146 may be constant on the
surface of the rotating cylinder head 140, or their width may be
wider on the bottom than on the top to help compensate for
frictional pressure drop and to help deliver a depth-independent
flux of higher proppant concentration fluid into the created
vortex. The rotation rate of the head 140 is associated with the
frequency of oscillation of the proppant concentration in the
fractures 56. Accordingly, the rotation rate of rotating head 140
may be controlled by, for example, a motor to produce predetermined
results. In other embodiments, a propeller may be attached to an
outer surface of the rotating head 140 so the lower proppant
concentration fluid 150 may be used to control the rotation rate of
the rotating head 140. A propeller-like structure also may be
located at an internal wall of the rotating head 140 such that the
pumping rate of the higher proppant concentration stream 142
controls the rotation rate of the head 140. In other applications,
the rotating head 140 may be designed so that the slots 146 direct
the streams of higher concentration proppant in a tangential
direction to the outer surface of the head 140 to create inertial
forces which rotate the head 140.
[0075] As illustrated in FIG. 23, the spiraling concentration
distribution leads to an oscillating proppant concentration in a
radial direction fracture. The oscillation caused by perforations
58 acting in concert with higher concentration proppant streams 142
and lower proppant concentration fluid 150 creates proppant
structures 52 in the fractures 56 extending into surrounding
formation 54. In this example, the proppant structures 52 are
generally created as concentric regions 152, e.g. rings, of higher
proppant concentration separated by lower concentration regions
154, e.g. rings, extending radially outward into the fractures 56.
It should be noted that the rotating head 140 can be used to
discharge streams of low proppant concentration fluid while the
higher proppant concentration fluid is pumped down through the well
external to the tubing and rotating head 140.
[0076] The orientation of the pattern of proppant concentration
oscillation has an impact on the fluid production rate coming from
the fracture 56. The oscillation makes the proppant placement not
only inhomogeneous but also anisotropic. Consequently, the
conductivity of such proppant-loaded fractures may be direction
dependent. In the example illustrated in FIG. 23, the higher
proppant concentration sections 152 are generally parallel with the
casing 80 and the fracture 56 has higher conductivity in a
direction generally parallel to the casing. In some applications,
the higher conductivity direction may be changed through, for
example, an anisotropic placement of proppant such that
conductivity is higher in the direction generally perpendicular to
the casing 80.
[0077] Referring generally to FIG. 24, an example of an additional
portion 155 of tool 44 is illustrated. The additional portion 155
comprises an internal screw 156 located to affect fluid flow of
proppant laden fluid. In the example illustrated, the screw 156
does not utilize moving components but it forces pumped, proppant
laden homogeneous fracturing fluid to rotate, as indicated by
arrows 158. In this example, the axis of rotation may coincide with
the axis of the well. As the pumped, fracturing fluid moves
downwardly, it rotates simultaneously and this rotation generates a
centrifugal force. The centrifugal force enriches the fracturing
fluid with high density proppant particles in the radially outward
region while the proppant concentration of the fluid becomes lower
along a center, open region 160 of screw 156. The separation is
based generally on the same principle as cyclonic separation.
However, in cyclonic separators the final direction of the low
particle concentration fluid is altered and moved opposite to the
gravitational force while the higher particle concentration fluid
stream is moved in the direction of gravitational force. In the
embodiment illustrated in FIG. 24, however, both the high and low
proppant concentration streams move downward toward the region of
perforations 58 while rotating, as illustrated in FIG. 25. The high
and low proppant concentration streams are indicated in FIG. 25 by
the low proppant concentration stream 162 and the high proppant
concentration stream 164 moving downwardly within casing 80 toward
the perforations.
[0078] Referring generally to FIG. 26, another embodiment of at
least a portion of tool 44 is illustrated in which a plurality of
tubes 166 is attached to some of the perforations 58. In this
embodiment, the length of tubes 166 is less than the internal
radius of the well. As illustrated, other perforations 58 do not
include tubes 166. The arrangement enables creation of perforation
belts 168, 170 arranged sequentially along a desired length of the
well, as illustrated in FIG. 27. In this example, the first belts
168 are created by the generally orthodox perforation regions
having no tubes 166, and the second belts 170 are created by the
regions of perforations which include tubes 166. Because of the
high pressure inside the well, the fracturing fluid is pushed
through the perforations 58 in both belt regions.
[0079] The concentration of proppant becomes higher in the fracture
region which is close to the orthodox perforations 58, and the
concentration of proppant becomes lower in the belt or fracture
regions close to the tubes 166. The orthodox regions and the
regions including tubes 166 may be alternated sequentially in a
vertical direction along the well so that the proppant
concentration is oscillated in the fracture along the vertical
direction. This leads to an anisotropic proppant placement in which
the conductivity of the proppant filled fracture is higher in a
direction generally perpendicular to casing 80. As illustrated in
FIG. 27, high proppant concentration regions 152 (proppant
structures 52) and low concentration proppant regions 154 extend
outwardly from and are generally perpendicular with respect to
casing 80. In some environments, the generally perpendicular
orientation of regions 152, 154 may lead to hydrocarbon or other
fluid production rate increases.
[0080] Depending on the well fracturing treatment (or other type of
subterranean treatment application) and on the desired function of
the treatment, the tool 44 and the overall system may comprise a
variety of configurations, systems, and components. For example,
the tubing string delivery system may be designed to deliver the
proppant and the proppant fluid along an individual flow path or
along a plurality of flow paths for combination at the downhole
tool. Additionally, each of the embodiments described above may
utilize a variety of additional, related, or other components
designed to facilitate the generation of heterogeneous proppant
structures. Furthermore, the embodiments, or portions of the
embodiments, may be used in combination with many types of proppant
and proppant carrier fluids. In some applications, a separate
stream or streams of clean fluid, e.g. fluid having a lower
concentration proppant or having no proppant 48, is routed downhole
along a separate path or paths for recombination with the
heterogeneous proppant structures. The heterogeneous proppant
structures may be transported through a casing into fractures or
through perforations formed in an open wellbore wall.
[0081] The generation of heterogeneous proppant structures may be
employed to improve the conductivity along fractures formed during
fracturing operations. However, generation of heterogeneous
proppant structures at a subterranean location and the local
placement of those heterogeneous proppant structures may be
employed in a variety of subterranean operations, including
non-well related operations.
[0082] Although a few embodiments of the system and methodology
have been described in detail above, those of ordinary skill in the
art will readily appreciate that many modifications are possible
without materially departing from the teachings of this disclosure.
Accordingly, such modifications are intended to be included within
the scope of this disclosure as defined in the claims.
* * * * *